Fracturing of earth formations is well known in the oilfield and other areas to improve the producibility and/or the injectivity of a well. The treatment of a well with a fracture can be an expensive procedure, with a high variability of results dependent upon the characteristics of the target formation. The control parameters defining the fracture treatment (e.g. including fluids, proppants, or acids utilized, pumping rates, etc.) are largely but not completely controllable. However, many important characteristics of the formation (or the environmental variables), for example the permeability or the in-situ stresses, are not always known with certainty. Therefore, it is important to design the controllable aspects of the fracture treatment accounting for the characteristics of the formation. Presently available optimization routines can find optimized parameters when the environment variables are known, but do not provide confidence that a true optimum is being designed where one or more environment variables are unknown. A method for optimizing fracture treatments that allows for environmental variables of varying certainty is desirable.